Sleeping Bags
- Match your bag's comfort rating with the coldest nighttime temperatures you expect to encounter.
- Bags using down insulation are lighter (providing a higher "warmth-to-weight" ratio) than bags using synthetic fill. They also compress into smaller shapes and last longer.
- Synthetic-fill bags can provide some insulation even when wet, and they dry out fairly quickly. Plus, for the same temperature rating, they cost less than down bags.
- A bag's shape matters. Mummy-style bags insulate most effectively and are your best choice for colder, high-elevation conditions; rectangular bags give you more room to change sleeping positions but offer more space that your body must heat up.
How Do Sleeping Bags Work?
Sleeping bags keep you warm by trapping and holding a layer of "dead" (non-circulating) air next to your body. This air, which is warmed by your body heat, forms a barrier between you and colder air or cold surfaces.
When evaluating bags, consider these key factors:
- Comfort rating
- Insulation (down or synthetic fill)
- Weight
- Size when compacted
- Shape
A sleeping bag's temperature or "comfort" rating identifies the most extreme temperature the bag is designed to accommodate. When you hear a bag described as a "+20 bag," it suggests most users should remain comfortable if the air temperature drops no lower than 20 degrees Fahrenheit.
Are such ratings infallible? No. Humans all have different metabolic rates, and no industry standards exist that uniformly determine sleeping bag comfort ratings. Instead, each manufacturer assigns a rating to its bags based on its own research. Therefore, use these numbers as a guide, not a guarantee. If you have trouble deciding between two bags, it's not a bad idea to select one that offers a little more warmth than you think you might need.
Many factors affect your ability to keep warm inside a sleeping bag:
- The insulating pad beneath your bag (when sleeping on frosty ground at high elevation, you need a full-length pad to keep you separated from the cold; when sleeping on snow or frozen ground, two pads are recommended)
- The presence/absence of a tent(a tent or bivy shelter traps an extra layer of dead air, warming it by up to 10 degrees)
- Your metabolism; you might be a "cold sleeper" (and thus one who prefers extra insulation when sleeping) or a "warm sleeper" (someone who kicks the covers off at home)
- Your gender(women frequently prefer bags with lower temperature ratings since they tend to "sleep colder" than men)
- Clothing worn while inside the bag (dry long underwear and clean socks are good choices on cold nights, plus they help keep body oils off your bag; a cap and neck gaiter keeps body heat from radiating away; fleece pants and jackets help on colder-than-expected evenings)
- Adjustments you make while in the bag (keep the bag zipped up and the hood cinched on cold nights; be careful to not breathe into the bag, since moisture has a negative effect on the insulation)
- Food in your stomach (the process of digestion helps produce warmth)
- Hydration(if you're not well hydrated the food won't help much)
- Even experienced campers and backpackers can be surprised by unexpectedly cold overnight conditions, particularly during trips in the spring and fall. It's smart to be prepared.
Tip—To be ready for those extra chilly nights, select a bag with a temperature rating that slightly exceeds the low end of the temperature range you expect to experience. If a +20° F bag sounds right for you, a +10° bag would probably work well, too. On warm nights, you can always vent a bag (by using the double zipper to open the area near your legs) or simply drape it over you, unzipped. It never hurts to be a little over-prepared.
Recognizing that comfort ratings are merely general guides. Sleeping bags are organized in the following categories:
| Bag Type | Comfort Rating (°F) |
| Summer Season | +35° and higher |
| 3-Season Bag | +10° to +35° |
| Cold Weather | -10° to +10° |
| Winter/Extreme | -10° and lower |
Please note: Even in summer, a +35° bag may leave you feeling chilly when sleeping in the high country. If you think of yourself exclusively as a warm-weather camper, yet plan to routinely camp at higher elevations (3,000 feet and up), choose a bag with a comfort rating at least in the 20s.
Down or Synthetic Insulation?
The insulation or "fill" inside a sleeping bag largely determines a sleeping bag's:
- Weight (and thus its "warmth-for-weight" ratio)
- Compressibility
- Durability
Down is the wispy, fluffy undercoating found just beneath the outer feathers of geese and ducks. This natural fiber is an extraordinary insulator. Goose down is preferred to down from ducks, prized because it is believed its plumes offer a higher "fillpower" (explained below).
Down's positives include:
- It offers tremendous warmth for surprisingly little weight (thus offering a superior "warmth-to-weight" ratio).
- It can be compacted into very small sizes.
- Its effectiveness outperforms synthetic insulation by years—even decades.
- If it gets wet, it is of no value until it dries—and in the field, that can take a long time.
- It is more expensive (keep in mind, though, that its resistance to deterioration makes it an outstanding long-term value).
- Down is graded according to fill power—meaning the number of cubic inches one ounce of down will displace. The higher the number, the better the insulation.
The advantages of synthetic fill include:
- It still provides some insulation when wet; plus it dries fairly quickly. It's less expensive than down. It's non-allergenic.
The shortcomings of synthetic fill are:
- It's bulkier than down (so it takes up more space when you're carrying it).
- It's heavier (it takes more weight to get the same warmth down provides).
- The filaments gradually degrade over time.
- The insulating "batts" of filaments are stiffer than down and do not drape over the contours of your body as effectively.
What about length? Do you need a "regular" or "long" model? The general rule is as follows: If you are no taller than 6 feet, choose a "regular" length bag. If you are up to 6-feet-6, you want a "long" bag.
Sleeping Pads
Sleeping pads perform 2 important functions -- first, they keep you comfortable when you're sleeping on hard, uneven ground. Second, they provide an important layer of insulation between you and the ground.
How Do They Work?
Sleeping pads insulate the same way that sleeping bags and clothing layers do. They trap and hold a layer of dead (non-circulating) air between your body and the cold (in this case, the cold ground). Your body gradually warms this layer of dead air and it becomes an insulating barrier. The isolative performance of a pad depends upon how much air it holds inside and how free that air is to circulate.
Step #1: Consider Your Plans
Think about:
- The kinds of weather you expect- if you're a fair-weather camper/backpacker, comfort will probably be more important than insulation. But if you hit the trail year-round or enjoy early spring or late fall trips, make sure you get a pad that provides protection from cold and wet conditions. It is recommended that you use two pads in snow or frozen conditions.
- The level of comfort you want while sleeping- some people prefer to save money, space and weight by sticking with very basic pads. Other prefer to spend (and carry) a little more to stay as comfortable as possible in the wilderness.
- How much extra weight you want to carry with you- Thicker, more comfortable pads can be heavy, which can cause problems on long backpacking trips. But if your trips are short or you're a car camper, weight will be less of an issue.
- How much space you have for storage- If you're backpacking with a full gear load, a light, compact sleeping pad will be far easier to pack. Space will be less of a problem if you're carrying all of your gear in your car, or boat.
Step #2: Consider Your Options
- Air mattresses- basic, inflatable air bladders
Pros - They're comfortable, adjustable and inexpensive.
Cons - They tend to be heavy, bulky and they can be punctured or ripped easily. Air inside is free to circulate, so they tend to be poor insulators. - Open-cell foam pads- sponge-like foam pads made up of tiny, open air cells
Pros - They're comfortable, lightweight and inexpensive. The tiny foam cells restrict air circulation, so they are also more effective insulators than air mattresses.
Cons - Open-cell foam is absorbent, which can cause problems in wet conditions. It's also less insulating than closed-cell foam (it must be cut about four times as thick to get the same insulation). Open-cell foam tends to be bulky, difficult to compress (for packing) and not very durable. - Closed-cell foam pads- made out of dense foam filled with tiny closed air cells
Pros - They're cheap, durable (won't pop when tromped on) and extremely insulative (almost no circulation of air in pad, so they can be cut thin yet still provide good insulation). Closed-cell foam is also non-absorbent.
Cons - They're relatively stiff and firm, with far less cushioning than open-cell foam (so you'll need a thicker, heavier piece to be as comfortable). - Self-inflating pads- open-cell foam pads wrapped in air-tight, waterproof nylon shells.
Pros - They're as comfortable as open-cell foam, but much more insulating (the nylon shell limits air circulation, while also protecting against water absorption). They're adjustable (built-in air valves let you control the amount of air inside and thus the firmness of the pad) and they're extremely compact when rolled up.
Cons - They're more expensive than the options listed above. Can be punctured or ripped (though field repairs are not difficult). Heavier than open- or closed-cell pads.
Step #3: Try Before You Buy
Sleeping pads come in a variety of styles, shapes and lengths. If possible, try out a number of different pads before deciding on a single model. This will help you get a feel for:
- How much cushioning you need to be comfortable
- How long and/or wide you want your pad to be (many models are cut short to save weight and packing space)
- How easy the pad is to inflate, deflate, and/or pack away
Finally, consider any extra pad features that might affect your decision -- like multiple air chambers (for a more custom adjustment), built-in pillows (for comfort), textured pad surfaces (for better insulation, less slip and more comfort) and tapered pad shapes that cut down on weight and bulk.